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  1. WHONOES

    Battery Level Indicator

    If all you want to do is see your battery voltage, use a small analogue panel meter. Simple and cheap.
  2. WHONOES

    How to convert hight voltage ac into dc?

    What on earth do you want to rectify 440V ac for. Sounds like a recipe for disaster. Instant death if you grab hold of the result.
  3. WHONOES

    What charger to use for LI-ion batteries

    Yes but, you still need to regulate the output volts to 4.2V per cell.
  4. WHONOES

    What charger to use for LI-ion batteries

    Don't use a 12V car charger it is not up to it.
  5. WHONOES

    What charger to use for LI-ion batteries

    Li-Ion cells have to be charged in a similar manner to sealed Lead Acid batteries. This is a 3 term process. The charge voltage should be set depending on the construction of the battery. Those with cathodes of Aluminium, Cobalt, Nickel or Manganese require 4.2V per cell though some Nickel...
  6. WHONOES

    Op amp problem

    Need a sketch of some sort to determine what you have done.
  7. WHONOES

    Hall effect ignition

    Look up RCEXL ignition systems. They are spark ignition systems intended for model aircraft engines. They use a Hall effect device to trigger the unit. Ignition timing is adjusted automatically over a range of 28deg (if I remember correctly) up to 8000rpm. They are used on some fairly large...
  8. WHONOES

    30W and 4x8W audio amplifier circuit?

    I have only ever used class AB or sometimes B. I have designed my own for the last 40 years or so with noise impossible to hear and distortion vanishingly small (at least in simulation). Preferring Fet O/P though they are a little more recent.
  9. WHONOES

    how to make Regulated power supply of 0 - 48V 5Amp using 24-0-24 V 5Amp center tapped transformer?

    The 48V rating refers to the transformer voltage at full load. When rectified and smoothed, the maximum current available will be 70% of the stated RMS current.
  10. WHONOES

    Bringing Voltage from 4 Volts to 1000 (or slightly more)

    Don't. 1000v especially at your proposed 100Khz is an instant killer. If you do manage to survive you will no doubt have severe RF burns.
  11. WHONOES

    30W and 4x8W audio amplifier circuit?

    Agreed. As I said it was a point of interest. Personally I would not use a class D for HI-FI as they are sonically inferior but, I am sure you disagree with that.
  12. WHONOES

    30W and 4x8W audio amplifier circuit?

    As a point of interest, you can easily calculate power supply requirements for what ever power output you want. First decide on how much RMS power you need then decide on the impedance of your speaker system. Next multiply RMS power by speaker impedance and extract the square root of that sum...
  13. WHONOES

    Resistors, Capacitors, Zener diodes... Why the funny values?

    No, I mean logarithmically.
  14. WHONOES

    Resistors, Capacitors, Zener diodes... Why the funny values?

    Resistor values are logarithmically spaced. There are a number of ranges all prefixed with E and they are E6, E12, E24, E48 and E96. This means that in the E6 range there are 6 values between1 and 10 then, E12 will have 12 values between 1 and 10 etc. Capacitor values follow the same principal...
  15. WHONOES

    12VDC Backup supply

    KISS Keep It Simple Stupid. Don't over think it. Keep the charge rate at a sensible level. Enough to run your device on standby and then have enough left over to charge you battery taking in to account self discharge.
  16. WHONOES

    12VDC Backup supply

    No. I have done a lot of stuff with rechargeable batteries from the MOD down. NI MH and NiCad batteries can be charged indefinitely at the 14 hour rate which is essentially charging at 10% of capacity. The 14Hr rate comes from the charge process only being 60% efficient.
  17. WHONOES

    30W and 4x8W audio amplifier circuit?

    Look up the LM1875 which is a Texas part and do as the data sheet instructs. They seem to be less than 4$ each and are not surface mount. If that's not good enough you may have to construct you own power amps which is not as much of a nightmare as it sounds.
  18. WHONOES

    12VDC Backup supply

    A small 9V rechargeable battery such as a PP3 in the UK or 6LR61 in the US would have a capacity of about 100mA hr at a discharge rate of 0.2mA you would get about 500 hours run time. But that assumes that your device will still run at 7V which is the level it will be at after 500 hours. You are...
  19. WHONOES

    Digital programmable CDI ignition for 2-stroke engines

    We use something similar on model aircraft. It is a small device that uses a magnet on the prop shaft to trigger a Hall effect sensor and produces a healthy spark. The fit various spark plugs. The timing is automatically adjusted depending on engine speed. We pay about £40 to 50 in the UK. They...
  20. WHONOES

    I found a cheap and great way to get rid of Rosin off of a PCB.

    IPA Isopropyl alcohol is the stuff to use. I have done so for many years. Undiluted car screen wash is usually IPA sometimes with a bit of detergent in it.
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